J. Martin, L. Jessie III, C. Flanagan, A. Richard-Bassett, M. Lockard

Willamette University, Salem, OR

Air displacement plethysmography (ADP) is considered one of the most accurate and accessible methods of body composition testing. Exercise prior to testing is known to influence ADP results, and is thought to be related to how the temperature, humidity, and compressibility of air inside the BOD POD changes as a result. PURPOSE: To examine the effect of exercising at a moderate intensity prior to ADP assessment on the results, and how temperature and humidity changes in the chamber may be related. METHODS: 10 healthy college-aged participants were recruited for this study. Body composition, as well as ADP chamber temperature and humidity, were measured before exercise, immediately post-exercise and two hours post-exercise. Participants exercised at ≥70% maximal heart rate for 15 minutes. The difference between conditions was analyzed via paired t-tests and least-square regression tests. RESULTS: No trend of note was found with temperature, as from pre-exercise to post-exercise and post-exercise to two hours post-exercise, means increased by 1.040 (p=0.013) and 0.390 (p=0.540) degrees C, respectively. Humidity, on the other hand, increased by 12.3% after exercise (p=0.001) and subsequently returned to the same level as the pre-exercise mean after two hours. Body composition results (specifically percent body fat) also decreased significantly after exercise by 2.91% (p=0.000). After two hours, the body composition results increased by 2.37% (p=0.000) from post-exercise levels, not quite returning to pre-exercise conditions but approaching them. No correlation was found between temperature and body composition results in this experiment (r=-419, p=0.725), but a strong negative correlation approaching significance was found between humidity and body composition results (r=-0.985, p=0.112). CONCLUSION: A single bout of exercise does affect body composition results as determined by ADP. In addition, humidity shows a very strong negative correlation to ADP body composition results, possibly due to an increased presence of isothermal-like air in the BOD POD chamber following exercise.

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